Resources in a Long Term Evolution (LTE) or Long Term Evolution Advanced (LTE-A) system are divided into radio frames (which are also referred to as system frames) in time. One radio frame includes 10 subframes, a length of one subframe is 1 ms, and one subframe includes two timeslots. Radio frames are numbered from 0 to 1023, and subframes of each radio frame are numbered from 0 to 9. For a normal cyclic prefix (CP), each timeslot includes seven symbols, and for an extended CP, each timeslot includes six symbols. The resources are divided into subcarriers in frequency. One physical resource block (PRB) is defined as one timeslot in time and 12 subcarriers in frequency.
In the LTE or LTE-A system, system information is classified into a master information block (MIB) and a system information block (SIB).
Generally, the MIB is carried on a physical broadcast channel (PBCH). In the existing LTE or LTE-A system, the PBCH is mapped to four consecutive radio frames, and a period is 40 ms. A start radio frame of the radio frames to which the PBCH is mapped meets SFN mod 4=0, where SFN is a number of the radio frame, and mod ( ) is a modulo operation. The PBCH is mapped to the first four symbols in the second timeslot of a subframe 0, and occupies middle six PRBs in system bandwidth, that is, occupies middle 72 subcarriers. A schematic diagram in a case of a normal CP is shown in FIG. 1.
There are multiple types of SIBs, which are mainly a SIB1, a SIB2, . . . , and a SIB16. A sending period of the SIB1 is 80 ms, that is, eight radio frames, a start location of each period is a radio frame whose SFN mod 8=0, and repeated sending is performed in subframes 5 in radio frames whose radio frame numbers meet SFN mod 2=0 in 80 ms, that is, repeated sending is performed every 20 ms. Other types of SIBs are included in several system information (SI) messages according to different scheduling requirements (such as periods). Each type of SIB is included in one SI message, and only SIBs with a same period can be included in one SI message. An SI message is allowed to be sent within specific duration in time, and the duration is referred to as an SI window. A transmission period of an SI message, a length of an SI window, and a mapping relationship between another type of SIB and an SI message are dynamically scheduled by using the SIB1. In each subframe for transmitting a SIB, the SIB is carried on a physical downlink shared channel (PDSCH), and is scheduled by using downlink control information (DCI) carried on a physical downlink control channel (PDCCH), that is, a frequency resource, an encoding rate, and the like used in SIB transmission are configured.
In the LTE or LTE-A system, user equipment (UE) needs to establish a connection to a network, and this process is generally referred to as a random access process. In the first step of the random access process, the UE sends a random access preamble to a base station. After detecting the random access preamble, the base station sends a random access response (RAR) to the UE. The RAR is sent in any subframe in a random access response window. In a subframe for sending the RAR, the RAR is carried on a PDSCH, and the PDSCH is also scheduled by using DCI carried on a PDCCH.
In the LTE or LTE-A system, a network needs to page (paging) corresponding UE, for UEs in an idle mode (Idle mode) when a service of the UE arrives, or for UEs in an idle mode or a connected mode when a system message needs to be changed or when an earthquake and tsunami warning service or a commercial mobile alert service is to be performed. A time resource for sending a paging message to the UE by the base station is determined according to a paging occasion (PO) and a paging frame (PF). One PF is one radio frame and includes one or more POs. One PO is one subframe, and the base station sends a paging message in this subframe. The PO and the PF are calculated according to a formula specified in a protocol.
In a subframe for sending a paging message, the paging message is carried on a PDSCH, and the PDSCH is scheduled by using DCI carried on a PDCCH.
The MIB, the SIB, the RAR, and the paging message may be referred to as public messages. The PDSCH is further used to carry unicast data in addition to the public messages, and the unicast data may also be referred to as dedicated data of UE. In the existing LTE or LTE-A system, regardless of whether the PDSCH carries the public message or the unicast data, the PDSCH always needs to be scheduled by using DCI carried on a PDCCH.
When a machine type communication (MTC) service is supported in the LTE or LTE-A system, coverage of an LTE or LTE-A network needs to be enhanced to send information in the LTE or LTE-A network in an enhanced manner, which ensures that UE in a basement or with poor channel quality can reliably communicate with the base station.
In the prior art, a method for sending a MIB in an enhanced manner is repeatedly sending a MIB in an existing system in a period of 40 ms. A MIB sent in an enhanced manner is referred to as enhanced sending of the MIB (or a PBCH burst, an enhanced MIB, or an enhanced PBCH). In the period of 40 ms, a manner of sending a MIB in an enhanced manner may be one of the following options: 1. An existing MIB is repeatedly sent only in subframes 0, and other symbols in the subframes 0 than the first four symbols in the second timeslots may be occupied for enhanced sending of the MIB. 2. The existing MIB is repeatedly sent in subframes 5 in odd radio frames and subframes 0. 3. The existing MIB is repeatedly sent in subframes 0 and another subframe in each of all radio frames. 4. The existing MIB is repeatedly sent in subframes 0 and three other subframes in each of all radio frames. A period of 40 ms for sending a MIB in an enhanced manner is one of the following options: A. The MIB is sent in an enhanced manner in each period of 40 ms. B. The base station decides whether the MIB is sent in an enhanced manner in a period of 40 ms, and the base station may dynamically choose whether to send the MIB in an enhanced manner. C. It is decided, based on a predefined pattern, whether to send the MIB in an enhanced manner in a period of 40 ms, where the predefined pattern specifies that among several consecutive periods of 40 ms, the MIB is sent in an enhanced manner in which period of 40 ms, and the MIB is not sent in an enhanced manner in which period of 40 ms. The MIB is also sent in an enhanced manner on middle six PRBs in system bandwidth, that is, 72 subcarriers.
Repeated sending is also an effective method for sending, in an enhanced manner, information carried on a PDSCH. When the PDSCH is used to carry a SIB, a method for sending the SIB in an enhanced manner is still using a SIB type in an existing system. A subframe for sending the SIB in an enhanced manner is the same as an existing subframe for sending the SIB, and a change cycle of the SIB is prolonged. In a change cycle of a SIB, the base station sends same SIBs in subframes for sending a SIB, so that UE can accumulate these same SIBs to improve performance. Alternatively, a new subframe is defined to send an existing SIB in an enhanced manner, the newly defined subframe is different from the existing subframe for sending the SIB, and the SIB is repeatedly sent in the newly defined subframe. Another method for enhancing the SIB is defining a new SIB for UE in a basement or with poor channel quality. For example, a SIB17 or a SIBm is defined, and the new SIB is repeatedly sent in multiple subframes for multiple times, to ensure receiving performance of the UE in the basement or with poor channel quality. When the PDSCH is used to carry a paging message, a method for sending the paging message in an enhanced manner is defining additional PF and PO resources in a new manner of calculating a PF and a PO, and repeatedly sending a same paging message on the additional PF and PO resources. When the PDSCH is used to carry an RAR or unicast data, repeatedly sending, in multiple subframes, a same PDSCH on which the RAR or the unicast data is carried is also an effective method for enhanced sending.
When the information in the LTE or LTE-A network is to be sent in an enhanced manner, when a PDSCH is used to carry unicast data, the unicast data to be sent in an enhanced manner is scheduled by using DCI carried on a PDCCH. When the PDSCH is used to carry a public message, the public message to be sent in an enhanced manner may be scheduled by using DCI carried on a PDCCH, or the public message is not scheduled by using DCI carried on a PDCCH, and is sent in an enhanced manner by using predefined parameters such as a frequency resource and an encoding rate.
When the DCI carried on the PDCCH is used to schedule the PDSCH, the DCI also needs to be sent in an enhanced manner. Repeatedly sending same DCI in multiple subframes is an effective method for sending the DCI in an enhanced manner. The DCI that is repeatedly sent includes resource block allocation that is used to configure a frequency resource used for a PDSCH in multiple subframes.
However, in the prior art, in a method for sending information in an enhanced manner, because a PDSCH that carries unicast data is scheduled by using DCI, and several frequency resources in system bandwidth are configured by means of resource block allocation in the DCI, the several frequency resources or PRB is used to send the unicast data in multiple subframes. The frequency resources configured by means of the resource block allocation in the DCI may overlap a frequency resource used to send a MIB in an enhanced manner, and among the multiple subframes for sending the unicast data by using the frequency resources configured by means of the resource block allocation in the DCI, some subframes are not subframes for sending the MIB in an enhanced manner, and some subframes are subframes for sending the MIB in an enhanced manner. Therefore, enhanced sending of the unicast data may conflict with enhanced sending of the MIB. Likewise, when the PDSCH carries a public message and is scheduled by using the DCI, enhanced sending of the public message may conflict with enhanced sending of the MIB.
When the PDSCH carries the public message and is not scheduled by using the DCI, and the public message is to be repeatedly sent in multiple subframes by using a predefined frequency resource, the predefined frequency resource is used in all the multiple subframes. The predefined frequency resource may overlap a frequency resource used for enhanced sending of the MIB; therefore, when the multiple subframes include a subframe for sending the MIB in an enhanced manner, enhanced sending of the public message may conflict with the enhanced sending of the MIB.
In addition, in a case in which the base station dynamically decides whether a MIB is sent in an enhanced manner in a period of 40 ms, from a perspective of the UE, the UE does not know whether the base station sends the MIB in an enhanced manner in a period of 40 ms, and therefore, does not know whether enhanced sending of unicast data or a public message carried on a PDSCH conflicts with enhanced sending of the MIB.
In addition, when the PDSCH is used to carry different information, in multiple subframes for sending information in an enhanced manner, a frequency resource configured by means of resource block allocation in DCI or a predefined frequency resource is used to send the information in an enhanced manner. There may be an overlapping frequency resource between frequency resources configured or predefined for enhanced sending of the different information; therefore, in some subframes, enhanced sending of at least two types of information in a SIB, an RAR, a paging message, or unicast data may conflict with each other. There may also be an overlapping frequency resource between a frequency resource configured or predefined for enhanced sending of information and a frequency resource configured for sending of information; therefore, in some subframes, enhanced sending of a SIB, an RAR, a paging message, or unicast data may conflict with sending of at least one type of the information. Enhanced sending of unicast data of different users may conflict with each other, or enhanced sending and sending of unicast data may also conflict with each other. An effective conflict resolving solution is absent from the prior art.